The subject invention relates to an improved design for a device that removes aerosol from crankcase gasses from an internal combustion engine for return to an air intake manifold.
Increasingly strict emission laws for internal combustion engines have led to the development of devices to both improve engine efficiency and reduce volatile emissions to the environment. One method to do so has involved recycling blowby gasses from a crankcase. Generally, this process involves recycling gasses that have been stripped of combustion contaminants and returning the gasses to an engine air intake manifold for reintroduction to a combustion chamber. Devices that perform this process typically include a series of baffles having a filter media therebetween. The baffles variously reduce the flow rate of the gasses while the filter media removes aerosol from the gasses. A device with this design requires replacement when the filter media fouls causing a terminal reduction of gas flow.
In the alternative, centrifugal devices have been utilized to filter the blowby gasses for return to an air intake manifold. A centrifugal device provides adequate filtration without the inclusion of a filter media that can foul. However, the device includes moving parts that require replacement when worn.
A device that can perform the requisite filtration without either fouling or wear is preferable over the prior art.
The present invention overcomes the difficulties found in known filters by providing a multistage filter assembly. The assembly of the present invention for removing aerosol from crankcase gasses being returned to an air intake manifold includes a housing having a housing wall defining a top portion and a base with at least one drain. An inlet line extends through the housing wall communicating with a crankcase. An outlet line extends through the top portion for communicating with an air intake manifold. An inertial separator is attached to the inlet line and has a screen through which the crankcase gasses pass and an impacter plate for obstructing aerosol suspended in the gasses. A sheet wound in spaced convolutions to define a spiraled path from the exterior to a central space conveys gasses from the inertial separator to the central space. A thermal interception tube located in the central space receives gasses and has a porous wall for gasses to pass therethrough and a tube opening at one end for egress of gasses.
The invention also incorporates a method for separating aerosol from crankcase gasses. The steps of separating the aerosol from crankcase gasses include the first step of, passing the gasses through a screen and impacting the gasses against an impacter plate for obstructing the aerosol suspended in the gasses. The second step includes circulating the gasses in a spiraled path to a central space to remove the aerosol from the gasses. The final step includes filtering the gasses through a filter disposed in the central space. The cleansed gasses are subsequently returned to an air intake manifold for reintroduction to the combustion chamber.
The subject invention yields improved removal efficiency over the prior art through the utilization of separate filtration stages. In addition, utilizing drain options described herein connected with an engine sump provides periodic or continuous purging of the filtrate without requiring manual replacement or cleaning. Also, the absence of mechanical parts utilized within a centrifugal filter reduces or eliminates the need for service. Finally, the elimination of filter media provides for a longer lasting service free device.